I got the following question via e-mail:
Laetare Sunday is almost upon us and the servers at my church have been earnestly debating a question you’re better placed to answer than most. Is it the case, as people used to say in the 1960s, that rose vestments can only be worn on two days of the year, next Sunday and Gaudete Sunday? Shouldn’t they also be worn on the Saturdays previous for vigil masses in both forms of the rite and — in spite of the fact that Saturday vigils as a substitute for Sunday’s obligation were a novelty of the 60s — surely there must be licit EF vigils nowadays in places like the Brompton Oratory ? Secondly, what about using rose during ferial masses during either week ? I’m sure younger priests would be grateful for guidance.
First, yes, it is still the case that rose (rosacea) vestments can be used only two days of the year. Therefore, it is important to consider what is "day" is.
A liturgical day begins in the evening. So, for example, in the Novus Ordo when using the 2002 Missale Romanum on Saturday or the Vigil of a day of obligation, you use whatever Mass it for that Saturday until late afternoon, when you would start using the Sunday Mass texts (or proper Vigil Mass texts, as in the case of the day before Ascension Thursday.
So, for Laetare and Gaudete in the Novus Ordo, you can use rose vestments when celebrating the anticipated Sunday Mass on Saturday evening.
I would also add that we interpret laws in a way that favors our needs. So, the 1983 Code helps us understand that our Sunday can extend beyond the mere liturgical day, all the way into the evening. So, if you had a Sunday Mass a, say, 8 pm, it is still Sunday, even though we are past Second Vespers and one might be able to called it, liturgically speaking, already Monday. Again, laws favor our needs.
As far as the Extraordinary Form is concerned, I don’t know about places using the older Missale Romanum on a Saturday evening as an anticipated Mass for the Sunday, that is, celebrating the Sunday Mass on Saturday evening. Maybe there are such places, but I doubt it. Perhaps someone will have heard of one and will post a comment. In any event, if someone were saying the Laetare Sunday TLM on a Saturday evening, they would I suppose use rosacea if available. Why not? It is liturgically already Laetare Sunday.
However, if a correct TLM for the Saturday is celebrated on a Saturday evening, at the time a Novus Ordo anticipated Sunday Mass would be offered, one fulfills ones Sunday obligation, even though the Mass used was the Saturday Mass and not the Sunday Mass. The 1983 Code of Canon Law states that we fulfill our obligation by participating at Mass in a Catholic Rite on the Sunday, or day of obligation, or on the vigil of the Sunday or day of obligation. The texts don’t have to be of the Sunday, but it does have to be Mass in a Catholic Rite.